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methylnaltrexone

Pronunciation: METh IL nal TREX own

Brand: Relistor

What is the most important information I should know about methylnaltrexone?

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You should not use this medication if you are allergic to methylnaltrexone, or if you have a blockage in your stomach or intestines.

Before you use methylnaltrexone, tell your doctor if you have severe or ongoing diarrhea.

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Prepare your dose in a syringe only when you are ready to give yourself an injection. After loading a syringe, if you cannot give the injection right away keep it at room temperature and use it within 24 hours.

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Methylnaltrexone may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

What is methylnaltrexone?

Methylnaltrexone is a special narcotic drug that blocks certain effects of other narcotic medicines.

Methylnaltrexone reduces constipation caused by narcotic medications that are often used to treat pain in people with terminal illness.

Methylnaltrexone works by preventing this side effect without reducing the pain-relieving effects of the narcotic.

Methylnaltrexone is usually given after laxatives have been tried without successful treatment of constipation.

Methylnaltrexone may also be used for purposes not listed in this medication guide.

What should I discuss with my health care provider before receiving methylnaltrexone?

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You should not use this medication if you are allergic to methylnaltrexone, or if you have a blockage in your stomach or intestines.

To make sure you can safely use methylnaltrexone, tell your doctor if you have any of these other conditions:

  • cancer;
  • a stomach ulcer; or
  • colitis or other intestinal disorder.

FDA pregnancy category B. Methylnaltrexone is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

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It is not known whether methylnaltrexone passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How is methylnaltrexone used?

Methylnaltrexone is injected under the skin. You may be shown how to use injections at home. Do not self-inject this medicine if you do not fully understand how to give the injection and properly dispose of used needles and syringes.

This medication is usually given once every other day, but not more often than once every 24 hours.

Methylnaltrexone can produce a bowel movement within 30 minutes after injection.

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Prepare your dose in a syringe only when you are ready to give yourself an injection. After loading a syringe, if you cannot give the injection right away keep it at room temperature and use it within 24 hours.

Use a disposable needle only once. Throw away used needles in a puncture-proof container (ask your pharmacist where you can get one and how to dispose of it). Keep this container out of the reach of children and pets.

Each single use vial (bottle) of this medicine is for one use only. Throw away after one use, even if there is still some medicine left in it after injecting your dose.

Methylnaltrexone should look clear or slightly yellow in color. Do not use the medication if it has changed colors or has particles in it. Call your doctor for a new prescription.

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Store at room temperature away from moisture, heat, and light. Do not freeze.

What happens if I miss a dose?

Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

Do not use this medication more than once in a 24-hour period.

What happens if I overdose?

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Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include extreme dizziness, or feeling like you might pass out.

What should I avoid while using methylnaltrexone?

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Methylnaltrexone may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

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Do not use any other laxatives that your doctor has not prescribed.

What are the possible side effects of methylnaltrexone?

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Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

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Call your doctor at once if you have severe or ongoing diarrhea, stomach pain that will not go away, black or bloody stools, coughing up blood, or nausea or vomiting that are new or worsening symptoms.

Less serious side effects may include:

  • stomach pain, gas;
  • mild nausea or diarrhea;
  • dizziness; or
  • increased sweating.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect methylnaltrexone?

Before receiving methylnaltrexone, tell your doctor if you use any narcotic medication, such as:

  • buprenorphine (Buprenex, Subutex);
  • butorphanol (Stadol);
  • codeine (Tylenol with codeine);
  • hydrocodone (Lortab, Vicodin);
  • hydromorphone (Dilaudid);
  • levorphanol (Levo-Dromoran);
  • meperidine (Demerol);
  • methadone (Dolophine, Methadose);
  • morphine (Kadian, MS Contin, Roxanol);
  • nalbuphine (Nubain);
  • naloxone (Narcan);
  • oxycodone (OxyContin, Roxicodone, Percocet);
  • oxymorphone (Numorphan); or
  • propoxyphene (Darvon, Darvocet).

This list is not complete and other drugs may interact with methylnaltrexone. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

Where can I get more information?

Your doctor or pharmacist can provide more information about methylnaltrexone.


Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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